1. Field of the Invention
The present invention relates to a field emission display (FED) and a manufacturing method thereof, and more particularly, to a field emission display (FED), which is maintained in a high vacuum state by absorbing gases in a display panel through the activation of a non-evaporable getter (NEG) layer that is formed on the front plate of the FED, and a manufacturing method thereof.
2. Description of the Related Art
In a field emission display (FED), several hundreds to thousands of micro tips or carbon nanotubes (CNTs) per pixel are provided as an electron emission source on a back plate of FED, and a phosphor layer emitting a light by an electron from the electron emission source is formed on a front plate of FED. A gap between the front plate and the back plate of FED is usually about 200 μm to several mms and the display must be maintained in a high vacuum state so that electrons are moved without energy loss.
A conventional display using electron emission includes a cathode ray tube (CRT) in a TV set. Since the internal volume of the CRT is very large, it is comparatively easy that the CRT is maintained in a vacuum state. However, in the case of the FED, the internal volume of the display is very small, and thus, it is very difficult that the FED is maintained in a vacuum state. This is the reason materials generating gases are relatively widely distributed in the small internal volume of the FED, and thus, vacuum state of FED may be rapidly deteriorated by the gases that is generated from the materials. Thus, the FED must be manufactured in a high vacuum state, and this vacuum state has a great effect on the quality and lifetime of the FED.
FIG. 1 is a schematic cross-sectional view of a conventional FED, and FIG. 2 is a schematic projected top view of the conventional FED.
The conventional FED includes a front plate 10 and a back plate 20 that are spaced from one another by a gap. An anode 12 and a cathode 22 having a striped form are formed on the opposite inner surfaces of the front plate 10 and the back plate 20, respectively. A gate insulating layer 24 in which holes 24a are formed, is disposed on the cathode 22. A gate electrode 26 in which gates 26a corresponding to the holes 24a are formed, is formed on the gate insulating layer 24. An electron emission source 28 such as micro tip and carbon nanotube (CNT), is formed on the surface of the cathode 22 that is exposed at the bottom of the holes 24a. 
A phosphor layer 14 having colors corresponding to pixels are coated on the anode 12, and a black matrix 16 for improving contrast and color purity is formed among the phosphor layer 14. A plurality of spacers 18 for maintaining the gap between the front plate 10 and the back plate 20 are positioned between the front plate 10 and the back plate 20, and a sidewall frame 30 for sealing a display panel is positioned at edges between the front plate 10 and the back plate 20.
An exhausting path 40 for exhausting an internal gas is formed at one side of the back plate 20, and a sealing cap 40a for sealing the outlet of the exhausting path 40 is formed at the outlet of the exhausting path 40. A gas path 42 through which the internal gas is flowed into is positioned at another side of the back plate 20, and a getter container 46 including a getter 44 for absorbing gases is connected to the end of the gas path 42.
In the FED having the above structure, the getter container 46 is protruded outwardly from the back plate 20, resulting in an increase in the total thickness of the panel including the getter container 46. Since the absorption of gas is made through the gas path 42 having a narrow section area with very large gas flow resistance, the effective absorption of the gas is difficult. The large gas flow resistance is caused from the narrow gap between the front plate 10 and the back plate 20 that are maintained at a 200 μm to several mms of interval as well as from the gas path 42. Due to the increase in gas flow resistance between the front plate 10 and the back plate 20, it is very difficult that an internal gas, in particular, a gas far from the gas path 42, is passed through the gap between the front plate 10 and the back plate 20 and the gas path 42. Accordingly, the internal gas cannot be effectively removed, and thereby there is a limitation in increasing internal vacuum level.